Physics Activity

Force, Work, and Distance

on an Incline

Purpose:

To investigate the relationship between the force required to move an object up an incline, the distance it moves, and the work done.

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Equipment:

inclined plane	spring scale
meter stick	ring stand
ring-stand clamp	dynamics cart

Equipment Diagram

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Discussion:

An inclined plane is such a simple device that many people find it difficult to think of it as a "machine" - but it is! It is easier to push a heavy load up an incline (ramp) than it is to lift it directly - that is, when you push or pull an object up an incline, it takes less force to move it than if you lifted it directly. However, you have to exert the force for a longer distance on the incline.

Length Measurements on the Incline

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Procedure:

1. Put the clamp on the ring stand to hold one end of the incline as shown in the diagram.
2. Measure and record the weight of the dynamics cart.
3. Measure and record:
   • the force, F, required to pull the dynamics cart up the incline
   • the length of the incline, l
   • the vertical height, h, that the incline lifts the cart
4. Move the clamp and/or the bottom of the incline to change its angle to the horizontal. Repeat step 3. (HINT: It may be easier to analyze the data in this activity if you leave the clamp where it is and change the incline angle by moving the bottom of the incline. This way the vertical rise, h, is the same for each trial.)
5. Repeat for several different incline angles.

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Analysis:

What pattern can you find between forces and distances on an incline? Support your claims. (Hint: The work done to move the cart up the ramp is Fl (the force times the length of the incline - force times distance), and the work done to raise the cart to the same height directly is Wh (weight of the cart times height lifted - also force times distance).)

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last update January 20, 2010 by JL Stanbrough